Fortran77 program for boundary element equations

A FORTRAN77 program for in-core solving of large unsymmetric sparse matrices commonly arising in the boundary element analysis is presented. The program makes use of a storage scheme such that a minimum number of zero entries are stored in the matrix during solution. The non-zero entries and a minimum number of zero entries and their addresses are written into two arrays. The row with minimum number of non-zero entries is used as the pivot row. The absolute maximum element in this row is used as the pivotal element to avoid problems due to instability. Gaussian elimination is then performed on the compressed matrix which is stored in-core and the solutions are computed by back substitution. The program also illustrates the implementation of the solver in an interactive keyboard input mode or batch mode of execution. Error diagnostics are also generated for ill conditioned or singular matrices and dimensioning errors.